How does immutability impact performance or memory usage?

Immutability in programming, specifically in languages like Java, can significantly impact performance and memory usage. Immutability means that once an object is created, its state cannot be modified. This characteristic can lead to both advantages and drawbacks in terms of system efficiency.

Performance Impact

When an object is immutable, it can be shared freely across multiple threads. This eliminates the need for synchronization in multi-threaded applications, which can greatly enhance performance. However, creating new instances every time a change is needed can incur overhead, especially if used in scenarios requiring frequent modifications.

Memory Usage

Immutability can also affect memory usage positively and negatively. On the positive side, immutable objects can be optimized by the compiler, leading to reduced memory footprint due to object pooling. Conversely, too many objects being created in an immutable paradigm may lead to increased garbage collection overhead.

Example of an Immutable Class in Java

        public final class ImmutablePoint {
            private final int x;
            private final int y;

            public ImmutablePoint(int x, int y) {
                this.x = x;
                this.y = y;
            }

            public int getX() {
                return x;
            }

            public int getY() {
                return y;
            }

            public ImmutablePoint move(int deltaX, int deltaY) {
                return new ImmutablePoint(this.x + deltaX, this.y + deltaY);
            }
        }